Effects of conservation period and Lactobacillus hilgardii inoculum on the fermentation profile and aerobic stability of whole corn and sorghum silages

Abstract

BACKGROUND: Lactic acid bacteria inocula have been developed over the years to improve the aerobic stability of silages. The aims of the study were to evaluate the effect of various conservation periods and the use of Lactobacillus hilgardii inoculum on aerobic stability, fermentative profile and microbial population of corn and sorghum silages. Trials were carried out on two corns and one sorghum crops. The crops were untreated or treated with L. buchneri (LB, application rate 300 000 cfu g −1 FM), L. hilgardii (LH, application rate 300 000 cfu g −1 FM) and a combination (LB + LH, application rate 150 000 cfu g −1 FM each). Silos were opened after 15, 30, 100 and 250 days of conservation, and the silages were analysed for fermentative profile, microbial count and aerobic stability. RESULTS: During conservation, the inocula influenced the fermentation profile. The use of LH increased the aerobic stability at 15 and 30 days in one out of three trials, while after 100 and 250 days, the presence of LB alone or with LH led to greater stability. In all the trials, the acetic acid content increased, the yeast count decreased and the aerobic stability increased during the conservation period. CONCLUSIONS: This study has shown that a long period in complete anaerobiosis reduced yeast count and improved aerobic stability in all silages. The addition of LB was confirmed to be a good option for increasing aerobic stability of silages, whereas the effect of LH alone or in combination with LB on aerobic stability was not consistent between trials. Sample preparation and analysesAll replicates of pre-ensiled material and the silage were split into five subsamples. One subsample was analysed immediately for the DM content by oven drying at 80 ∘ C for 24 h. DM was corrected according to Porter and Murray,25 in order to consider the losses of volatile compounds that can take place at 80 ∘ C. The second subsample was oven-dried at 65 ∘ C to constant weight and was air-equilibrated, weighed and ground in a Cyclotec mill (Tecator, Herndon, VA, USA) to pass a 1 mm screen. The dried samples were analysed for total nitrogen, according to the Dumas method (method number 992.23), 26 using a nitrogen analyser (Primacs SN, Skalar, Breda, The Netherlands), for crude protein (CP) (total N × 6.25), for ash by ignition (method number 942.05), 26 for water-soluble carbohydrates (WSC), by the phenol sulfuric acid method, according to DuBois et al., 27 and for ether extract (EE), J Sci Food Agric 2019; 99: 2530-2540

Dynamic Succession of Microbiota during Ensiling of Whole Plant Corn Following Inoculation with Lactobacillus buchneri and Lactobacillus hilgardii Alone or in Combination

“…buchneri alone, but the concentration depended on the dry matter content, and overall, no statistical interactions were observed. When comparing the same treatments with a trial on whole plant corn ensiled at 363 g•kg −1 dry matter, the concentrations of acetic acid at 64 days correspond to the level reported by 250 days of incubation in Ferrero et al [57]. The differences between LB-LH and the Control in both studies is similar.…”

“…Although aerobic stability was not measured in our study, the LB-LH combination has been shown to improve aerobic stability in another study using the same forage [57], and several authors demonstrated that Lb. buchneri 40788 improves aerobic stability by reducing yeast counts [58].…”

Criteria for lactic acid bacteria screening to enhance silage quality

“…Several reviewed studies showed that there is an additional effect due to the metabolism of the strain used. Wheat, sorghum and whole-plant corn silages inoculated co-cultures of L. buchneri and L. plantarum which decreased pH, ammonia-N and fermentation losses, compared with silages inoculated with L. buchneri alone (Filya 2003 obligately heterofermentative LABs (Ferrero et al 2018). The addition of L. hilgardii and L. buchneri was more consistent in increasing aerobic stability in whole-plant corn silage trials than the L. hilgardii treatment on their own (Ferrero et al 2018).…”

“…Wheat, sorghum and whole-plant corn silages inoculated co-cultures of L. buchneri and L. plantarum which decreased pH, ammonia-N and fermentation losses, compared with silages inoculated with L. buchneri alone (Filya 2003 obligately heterofermentative LABs (Ferrero et al 2018). The addition of L. hilgardii and L. buchneri was more consistent in increasing aerobic stability in whole-plant corn silage trials than the L. hilgardii treatment on their own (Ferrero et al 2018). These authors suggested a synergistic effect between the two strains evaluated and attributed the increase in aerobic stability to the ability of L. hilgardii to dominate fermentation before L. buchneri is active.…”

“…A portion of the 1,2-propanediol present in the silage can be directly absorbed and transformed into glucose, and another portion is transformed into propionic acid before absorption (Yanbing et al 2017). This metabolite is generally found in higher concentrations in silages that have been inoculated with L. buchneri or L. hilgardii (Carvalho et al 2014a;Reis et al 2018;Ferrero et al 2018;da Silva et al 2019). Because of their diverse metabolism, LAB can perform other functions during ensiling to promote an increase in quality.…”